/Engine/Source/Runtime/AIModule/Classes/BehaviorTree/BTCompositeNode.h
Get index of child node (handle subtrees)
int32 GetChildIndex ( [FBehaviorTreeSearchData](API\Runtime\AIModule\BehaviorTree\FBehaviorTreeSearchData) & SearchData, const [UBTNode](API\Runtime\AIModule\BehaviorTree\UBTNode) & ChildNode ) const